Bicycles have, of course, been known and used for many years, and various methods for their propulsion have been proposed. The most common method is the almost universally seen system, which involves foot pedals connected to crank arms which drive a large sprocket wheel, the rotary motion of which is transmitted by an endless chain to a smaller sprocket wheel connected to the rear wheel of the bicycle.
Wilburn U.S. Pat. No. 608,241, however, shows a system using stirrups which are reciprocated vertically by the rider and are connected to drive a rack which meshes with the sprocket wheel or pinion connected to the rear wheel.
Price U.S. Pat. No. 384,543 proposes the use of levers or treadles pivoted at their forward ends and constructed to operate cranks which rotate pinions which mesh with second pinions connected to the front wheel of the bicycle.
Thorp U.S. Pat. No. 436,844 also uses treadle levers which are connected directly to aligned crank-wheels which, by a complicated system of meshing gears and friction wheels drive the rear wheel of the bicycle.
Booth et al U.S. Pat. No. 594,980 shows a system somewhat similar to that of Price, but the treadle or pedal levers replace pedals in the conventional type of drive and rotate the large front sprocket wheel which carries a chain which rotates the rear sprocket wheel and thus the rear wheel.
Greenison U.S. Pat. No. 1,427,589 uses levers or treadles which are pivoted to the bicycle frame and have elongated slots at their ends rearwardly of the back wheel. These slots receive crank arms connected to a sprocket wheel which in turn drives a second sprocket wheel connected to the rear wheel of the bicycle. The levers carry pedals at their forward ends.
McNeill U.S. Pat. No. 1,505,271 modified the Greenison patent by having the levers carried at the rear in slots in extensions of the bicycle frame and having the sprocket cranks provided with shafts passing through apertures in the levers.
In these prior constructions using levers or treadles, relatively complicated arrangements are shown involving cranks, wear-prone slots, or some other such construction which suffers from undue problems of friction and usually makes it necessary to apply substantial force, as in the conventional construction, in order for the rider to move the vehicle along the ground, particularly when starting up.